They used to be around and they made them for all the big gun calibers to facilitate handling drills. Last one I saw here was a 6Pdr 7Cwt with a long check from one end to the other, wanted over $300CDN. He still has it and is now out of business...
I guess it could be worse, there was one for sale in the UKa year back on MLU forum for £350. Then ship it here?